将 `decimal.NullDecimal` 类型转换为 int

Question

我正在使用类型为 decimal.NullDecimal（来自 github.com/shopspring/decimal）的变量，并希望转换其整数值以便能够将其与整数进行比较。我应该如何转换它的十进制值？
这是我的代码：

    import (
    // other packages
    "github.com/shopspring/decimal"
    )

    type BooksStores struct {
        PublisherShare decimal.NullDecimal `json:"publisher_share"`
    }
    var booksStores BooksStores

    err := c.ShouldBindBodyWith(&booksStores, binding.JSON)

    if err != nil {
        c.JSON(http.StatusUnprocessableEntity, gin.H{
            "error": err.Error(),
        })
        return
    }

    publisherShare := booksStores.PublisherShare


    // Here I want to compare the `publisherShare` value with 0 and 100
    if publisherShare < 0 || publisherShare > 100 {
    // DO SOMETHING
    }

这是我尝试过的方法，但 none 没有成功：


import "https://github.com/spf13/cast"


cast.ToInte(publisherShare) 
cast.ToInte(&publisherShare)
cast.ToInt(publisherShare.Decimal)
cast.ToInt(publisherShare.Decimal)
// but it is casted to zero, I have to use `decimal.NullDecimal` type
// due to the database considerations (later I have to update something)

我认为我应该使用 github.com/shopspring/decimal 包中的 Cmp 方法来比较 publisherShare 值与数字。

Answer 1

由于并非所有任意精度的小数都可以表示为 Go 整数，我想说你应该使用 decimal.NewFromInt(...) 将你的 int 转换为小数，然后使用 decimal.GreaterThan 之类的东西进行比较:

package main

import (
    "fmt"

    "github.com/shopspring/decimal"
)

func main() {
    // Let's say dec is the decimal we want to compare
    dec := decimal.NewFromInt(42)

    // We compare it to 100
    h := decimal.NewFromInt(100)

    if dec.GreaterThan(h) {
        fmt.Println("> 100")
    } else {
        fmt.Println("<= 100")
    }
}

Playground link

请注意，decimal.NullDecimal 仅包含一个 Decimal 和一个有效性标志，因此一旦您知道它是有效的，您只需从中获取 Decimal 字段，然后如上所示进行比较。

Answer 2

好的，现在问题解决了，我应该用var booksStores *BooksStores而不是var booksStores BooksStores。

    type BooksStores struct {
        PublisherShare decimal.NullDecimal `json:"publisher_share"`
    }
    var booksStores *BooksStores // Here is the place I had to change

    err := c.ShouldBindBodyWith(&booksStores, binding.JSON)

    if err != nil {
        c.JSON(http.StatusUnprocessableEntity, gin.H{
            "error": err.Error(),
        })
        return
    }

    publisherShare := booksStores.PublisherShare

    if publisherShare.Decimal.LessThan(decimal.NewFromInt(0)) || publisherShare.Decimal.GreaterThan(decimal.NewFromInt(100)) {
        // DO SOMETHING
        return
    }

将 `decimal.NullDecimal` 类型转换为 int

Cast `decimal.NullDecimal` type to int

casting

go